Plastic bobbin



Oct. 6, 1970 1 s, NEWMAN 3,532,291

PLASTIC BOBBIN Filed Nov. 27, 1968 22 l a a 2 INVENTOR. flR/UOLD s. AJEwMA/U ATTORNEX United States Patent 3,532,291 PLASTIC BOBBIN Arnold S. Newman, 1701-D Valley Park W., Augusta, Ga. 30904 Filed Nov. 27, 1968, Ser. No. 779,363 Int. Cl. B65h 75/10, 75/26 U.S. Cl. 242118.31 9 Claims ABSTRACT OF THE DISCLOSURE A lightweight bobbin formed of a one piece hollow molded cone of plastic having a thin skinned skeletal frame including a thin outer sheath and the frame of circumferentially spaced longitudinally extending runners interconnecting longitudinally spaced circumferentially extending runners on the inside of the cone. A plurality of circumferentially extending ridges are formed on the outer surface of the sheath to act as guides for filamentary material to be wrapped about the outer surface of the bobbin. The circumferential runners of the skeletal frame are lesser radial thickness than are the longitudinal runners so that when the cone is molded it is permitted to flex radially inwardly when being extracted from the mold to prevent marring of the ridges on the sheath. In one desirable construction the bobbin has a base diameter of approximately 2.75 inches and a height of approximately 9.6 inches with a slope of approximately 7 and 22 minutes with respect to the horizontal, the thickness of the outer sheath being approximately .022 inch to provide a lightweight but strong bobbin of ap proximately 32 grams weight when polypropylene plastic is used.

This invention relates to bobbins for filamentary material and, more particularly, to a lightweight bobbin formed of a one piece hollow molded cone of plastic material, such as polypropylene which is strong and can be cast to intricate detail to provide a conical bobbin of relatively long length about which a large quantity of filamentary material may be wrapped.

In the textile industry it is of important to provide a lightweight but strong bobbin capable of storing a large quantity of filamentary material. In use such bobbins are driven at very high peripheral speeds which is the speed of the filamentary material being applied to or withdrawn from the bobbin. In order to withstand the intense compressive forces or stresses to which such bobbins are subjected it is necessary that they be relatively strong to resist the bursting action imposed by the centrifugal force occasioned by the rotation of the bobbin.

An object of this invention is therefore to provide a light weight bobbin formed of a one piece hollow molded cone of plastic being of lightweight but strong construction to withstand the intense forces to which the bobbin is subjected in use.

A further object of this invention is to provide a one piece lightweight molded bobbin having a skeletal frame including a plurality of circumferentially spaced, longitudinally extending runners, and a plurality of interconnecting longitudinally spaced circumferentially extending runners, the circumferential runners being of materially less radial thickness than are the longitudinal runners to provide a structure capable of withstanding the bursting stresses imposed by the centrifugal force to which the bobbin is subjected, but which embodies sufiicient flexibility that the bobbin can compress radially inwardly to facilitate the extraction of the bobbin from the mold when it is being manufactured.

Another object of this invention is to provide a bobbin having a thin walled outer sheath having circumferentially extending ridges defining spaced grooves for the recep- 3,532,29l Patented (Pet. 6, 1970 tion and guiding of filamentary material to be wrapped about the bobbin, and which overlays a skeletal frame composed of a network of interconnected circumferential runners and longitudinal runners which provide a lightweight but strong bobbin capable of withstanding the stresses to which the bobbin is subjected in use.

Another object of this invention is to provide a molded bobbin of plastic material having a skeletal network consisting of a plurality of longitudinally extending runners converging from the base to the tip of the cone, and a plurality of axially spaced, lightweight, circumferential runners to resist the bursting stresses to which the bobbin is subjected due to the centrifugal forces exerted thereon, with the network or frame supporting an outer skin or sheath formed integrally with the skeletal framework to flex radially inwardly as the bobbin is extracted from the mold to avoid abrasion or other marring of the skin surface which is provided with close circumferential ridges formed on the outer surface of the sheath to act as guides for filamentary material to be wrapped about the bobbin.

Still a further object of this invention is to provide a lightweight but strong bobbin formed as a one piece molded plastic unit which can be produced economically and which is so proportioned as to provide a lightweight strong assembly.

Other objects and advantages of this invention will be apparent from the following detailed description considered in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevational view of my improved bobbin,

FIG. 2 is a sectional view taken substantially on the line 22 of FIG. 1 looking in the direction of the arrows, and

FIG. 3 is a bottom plan view of the bobbin.

Referring now to the drawings, the reference numeral 10 designates a bobbin formed of a one piece hollow molded cone of plastic having a base end 12 and a tip end 14. A skeletal frame 16 is formed of circumferentially spaced, longitudinally directed runners 18 of generally rectangular configuration as seen in cross section extending upwardly, as shown in FIGS. 2 and 3, from a thickened base 20 having the usual draft or angled surface 21 to facilitate extraction of the bobbin from the mold. A tapered reinforcing section 22 extends outwardly from the thickened base 20 as illustrated in FIG. 2, and the longitudinally-extending runners 18 blend into this tapered reinforcing section 22 and merge and blend into the surface of the thickened base 20 as shown in FIG. 2.

At the top end of the bobbin, the longitudinally-extending runners 18 merge and blend into dome-shaped reinforcing top 24 having a central aperture 26 therein which is defined by the mold but is not a part of this invention. The dome-shaped top 24 is of somewhat greater thickness than the side walls, and because of the inward curvature of the dome-shaped top, the longitudinal runners 18 blend with the dome-shaped top 24 to strengthen and rigidify the upper end of the cone or bobbin.

The skeletal frame 16 also has a plurality of longitudinally-spaced, circumferentially extending runners 28 of generally rounded configuration on the inside of the cone as shown in FIGS. 2 and 3. The circumferential runners 28 are of lesser radial depth than are the longitudinal runners 18, and have outer radial extremities 30 aligned with the outer radial extremities 32 of the longi tudinal runners 18. The cross sectional areas of the circumferential runners communicate with the cross sectional areas of the longitudinal areas of the longitudinal runners to form an interconnecting network of the skeletal frame 16. The rounded radially inner surfaces 34 of the circumferential runners 28 are of substantially less radial 3 thickness than are the generally rectangular longitudinal runners 18.

A thin walled outer sheath or skin 40 has its inner surface 42 aligned with and fused into the outer extremities of the circumferentially extending runners 28 and the outer extremities 32 of the longitudinally extending runners 18 of the skeletal frame 16 so that the cross sectional areas of the longitudinal runners 18 and the circumferential runners 28 and the thin walled outer sheath fuse together to form an integral structure. A one-piece hollow, molded cone of plastic is thus formed, the plastic material being contoured to provide a lightweight but strong structure.

The outer surface 44 of the outer sheath 40 may be formed with a plurality of circumferentially extending ridges 46 and 48 near the base end 12 and the tip end 14 of the bobbin, and an intermediate ridge 50 spaced at the approximate mid-section of the bobbin are provided to further strengthen the cone. The circumferential ridges 46 and 48 mark the lower and upper principal area on the bobbin for the reception of filamentary material to be Wrapped about the bobbin, and the intermediate ridge 50 tends to stabilize the mass of filamentary material intermediate the ends of the bobbin. It will, of course, be apparent that, if desired, additional intermediate ridges 50 may be employed between the lower and the upper ridges 46 and 48 to further provide guides to stabilize the filamentary material wrapped about the bobbin, and to strengthen the bobbin against centrifugal forces exerted thereon.

A plurality of shallow, circumferentially extending ridges 52 are formed between the lower and upper ridges 46 and 48. These ridges 52 are preferably of V shaped configuration and are preferably slanted angularly toward the tip of the cone to facilitate the removal of the cone from the mold and to provide between the shallow ridges 52 a plurality of longitudinally spaced grooves 54 for receiving and stabilizing the filamentary material on the bobbin. It will, of course, be apparent that the shallow ridges 52 function to further strengthen the bobbin against centrifugal forces exerted thereon as the bobbin is rotated at high speeds.

The bobbin 10 is formed by a molding process. The inner circumferentially extending runners 28 of generally rounded configuration are proportioned in such a manner that the side walls of the bobbin, including the longitudinally extending runners 18, flex inwardly as the bobbin is removed from the mold to prevent marring or scoring of the shallow ridges 52 formed on the outer surface of the sheath 40, and the circumferential ridges 46, 48 and 50 formed thereon.

While any suitable plastic may be used in the formation of the bobbin, I have found that polypropylene is a particularly desirable plastic since it has a high strength factor and good mold filling characteristics. As a result an integral bobbin is formed wherein the cross sectional areas of the longitudinal and circumferentially extending runners and the outer sheath are all interconnected for the reception of the molten plastic. An integral bobbin having a high degree of physical detail and contouring is provided. The bobbin has high strength characteristics capable of withstanding the centrifugal forces developed at the extremely high peripheral speeds encountered in the winding of filamentary material on bobbins.

While the bobbin can be made of varying sizes, it has been found that a bobbin having a height of approximately 9.6 inches with a base diameter of approximately 2.75 inches and a slope of approximately 7 and 22 minutes with respect to the horizontal, and wherein the outer sheath is approximately .022 inch thick will provide a lightweight bobbin of approximately 32 grams weight, which is very strong and capable of withstanding the stresses to which high speed bobbins are subjected in use.

While the invention has been described with particular reference to specific proportions, it will be understood that various changes may be made therein without departing from the spirit of the invention as defined by the following claims.

What is claimed is:

1. A bob-bin comprising a one-piece hollow molded cone of plastic having base and tip ends and including:

(a) a primary skeletal frame including a plurality of circumferentially spaced longitudinally extending runners on the inside of the cone;

(b) a plurality of longitudinally spaced circumferentially extending runners on the inside of the cone;

(0) the cross sectional areas of the circurnferentially extending runners communicating with the cross sec tional areas of the longitudinally extending runners;

(d) the outer radial extremities of the circumferentially extending runners being aligned with the outer radial extremities of the longitudinally extending runners; 1

(e) a thin-walled outer sheath having an inner and outer surface;

(f) the inner surface of the outer sheath being supported on the outer radial extremities of the frame of longitudinally extending runners and circumferentially extending. runners; and

(g) a plurality of longitudinally spaced circumferentially extending ridges formed in the outer surface of the thin-walled outer sheath and defining between the ridges a plurality of grooves to act as guides for filamentary material to be wrapped about the outer surface of the bobbin.

2. The invention defined in claim 1 wherein the bobbin has a base diameter of approximately 2.75 inches and a height of approximately 9.6 inches.

3. The invention defined in claim 2 wherein the bobbin has a slope of approximately 7 and Q2 minutes with respect to the horizontal when the center line of the Ibobbin is held in a horizontal attitude.

4. The invention defined in claim 1 wherein the inner surface of the thin-walled outer sheath communicates with the outer extremities of the longitudinally extending runners and is approximately .022 inch thick.

5. The invention defined in claim 4 wherein the weight of the bob bin is approximately 32 grams.

6. The invention defined in claim 5'- wherein the longitudinally extending runners and the circumferentially extending runners and the outer sheath are proportioned to permit flexing inwardly of the assembly to prevent marring of the circumferentially extending grooves when the bobbin is extracted from a mold.

7. The invention defined in claim 6 wherein the circumferentially extending runners are of substantially less thickness radially than are the longitudinally extending runners to permit radially inward flexing of the assembly to facilitate extraction of the assembly from the mold.

8. The invention defined in claim 1 wherein the bobbin is formed of polypropylene.

9. The invention defined in claim 1 wherein the circumferentially extending ridges formed in the outer surface of the outer sheath are of V shaped configuration and are slanted toward the tip end of the cone.

References Cited UNITED STATES PATENTS 949,641 2/1910 Anderson 242-1187 2,535,188 12/1950 Beckner 242-11832 3,403,872 10/1968 Williams et al. 242ll8.31

GEORGE F. MAUTZ, Primary Examiner US. Cl. X.'R. 242118.32 

